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| - Nanoconfinement Revealed in Degradation and Relaxation Studies of Two StructurallyDifferent Polystyrene−Clay Systems
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| - Degradation and relaxation studies have been performed on two polystyrene (PS)−montmorillonite claynanocomposites, one of which has an intercalated PS−clay structure and the other an exfoliated PS−claybrush structure. Compared to virgin PS, both nanostructured materials have demonstrated the followingsimilarities: (a) a high yield of α-methylstyrene in the degradation products as measured by infraredspectroscopy; (b) larger values of the activation energy of the thermal degradation as determined byisoconversional kinetic analysis of thermogravimetric data; and (c) larger values of the activation energy forthe glass transition as found from the frequency dependence of the glass transition temperature measured bymultifrequency temperature-modulated differential scanning calorimetry. These effects are taken as structureindependent manifestations of nanoconfinement of the PS chains in the PS−clay materials. Heat capacitymeasurements have been employed to evaluate the size of the cooperatively rearranging region, VCRR, that isfound to be structure dependent. Compared to its value in virgin PS, VCRR has markedly increased in theexfoliated PS−clay brush system but remained practically unchanged in the intercalated PS−clay system.
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